Crown caps for containers



R. M. BERGLUND CROWN CAPS FOR CONTAINERS Filed Dsc. 18, 1955 Feb. 5, 1957 United States Patent i CROWN CAPs FOR CONTAINERS Ralph M.- Bergland, Burlingame, Calif. j Applieatien neeember 1s, '1953, serielNe. 399,018

7 Claims'. (cl. 21S-46)l This invention relates to an improved crown c ap of the type which maybe removed from the container without benefit of a separate implement. The invention is herein illustratively described by reference to its presently preferred formY as applied to a conventionalbeverage bottle, but it will be appreciated that other applications are contemplated and that various changes and modifications in respect to details of construction of the cap may be made without departing from the underlying essentials involved, x

The general conceptof a hand-removable crown cap operating on the principle of rupturing the cap by a tearing action in order to break the seal of its gasket with the container mouth is not new. It has beenembodied in caps with integral rigid levers and in caps with a flexible tear tab. The latter type proved the more promising due to their lesser bulkiness, .lower manu.- facturing cost and better adaptability to use with conventional or only slightly modified crimping and bottle capping machinery. vA common difficulty experienced with both types as heretofore developed, however, resided in the inadequate methods .used for weakeningthe cap along a preselected tearline. Thisewas usually accomplished by scoringthe cap material to a desired depth,

but to do so practicably with mass production methods. so that all caps would possess .uniformstrength' and'.y

rupturability was a very difficult matter. With common tinplate and other cap material in use, the scoring usually' so weakened the cap blank that it would not stand upi under the crimping operation, or the scored capwould not withstand the Vinternal container pressures sometimes developed (i. e. occasionally more than 100 p. s. i. with glass bottle. It has been evident that 'the convenience to consumers ofa hand-rupturable crown cap for bottles could more than'cor'npensate for the highercost of that type of container.

It is also a purpose of this "invention -to providean f Ice; 2,780,380

rupture strength imparted to the completed cap. The means providing a line of rupture on the capyare such that no unduly critical Ymanufacturing steps are involved.

In achieving the foregoing objectives lthe improved crown cap Vhas a slit and the severed edges of this slit are bonded together by a technique which imparts the desired low shear resistance tothe joint for the 'handrupture operation, yet a suflcient `strength to withstand the stresses of crimping, capping and container pressure. In the preferred formv the slit edges are` flanged outwardly of the cap to receive a lilletof binder substance, such as solder, therebetween, the slit extending in acontinuous line from the edge of the cap skirt, upwardly along the crest of one of the skirt flutes, thence radially inward across theftopfand terminating short of its center. A tear tabY formed as an integral ,extension of the `skirt at a location immediately adjacent' .basic respects there is not necessarily a limitation to specific materials and manufacturing techniques.

The foregoing and other features, objects and advantages of the improved crown cap will become more fully evident from the following `descriptionby reference to the` accompanying drawings.

Figure 1 isa, plan view of the improved crown cap as it appears just prior to the capping operation.

Figure 2 is asside elevation view .of the cap.

Figure 3 is a 'transverse sectional detail of the lilleted tear line or joint.,-

,Figures 4 and 5` are'dilerentside' elevation views of the improved crown cap-as crimped on the lip of a bottle. 1

Figure 6 -is a perspective view lillustrating use of the tear tab;to break thev container seal and remove the cap.

Figure 7 is a plan view of a strip of material from which cap blanks are to be cut, and particularly illus-v tratesl the technique for forming the lleted tear line. f

-Figure 8 is a 'schematic diagram depicting a suitable i' mass production method for manufacturing the improved s crown cap. f Y

inexpensive crown cap of the type described which can f readily be manufactured with the use lof existing or known production machinery 'and which can be used in existing bottling .apparatus, with little or no modifications in either. The latter factor is' of particular' importance in View of the large present investments of the foodstuffs industries in such machinery. e v

Another object isthe provision ofra hand-rupturable crown cap in the manufacture of which it is a comparatively easy matter to establish and uniformly regulate the f The basic crown formation illustrated inthe drawings is'conventional, the cap 10 comprising va circular top plate 10a and the `crimped slightly divergent skirt y10b formed integrallyr therewith. .A cork disk '12( or equivalent Vgasket is retained within .the skirt against Kthe top. In a bottle capping machine this gasket is of cour'secorn'- pressed against the bottle lip as the capping head descends in the process of squeezing and permanently deforming the skirt 10b. The compressed skirt 10b is thereby molded into locking engagement with theusual cap-refrom theskirts lower edge, along the crest of one of the skirt ilutes 10b andradially inward across'the ytop 10a, terminating appreciably short of the center lilo. vThe slit edges are flanged .slightly outward .along their full length to form a groove between them whichreceives a fillet 14a of; solder or other suitable binder substance. For satisfactory accommodation of the sealing gasket 12 within the cap theexposed facev of the llet14a is made substantially flush with the immediately adjacent surfaces of the cap interior. A tear tab 16 projects from the edge of the i* skirt 10b immediately adjacentethe slit 14. Preferably the Patented Feb. 5, 1957 tear tab is an integral extension of the skirt itself, having a length and width just ample for it to be grasped conveniently between the fingers. A dimple 4or indentation 16a formed in the ltear tab near its projecting end enables it to begripped with aliirm hold and pulledwithout slipping between the fingers. With the cap'ona bottleB the tear tab 16 lies unobtrusively close alongside the neck thereof (Figure 4). The convex side of the indentation 16a then lies against the bottle neck and is accommodated beneath the overhang of the usual reinforcing bead or rib encircling the bottle beneath its lip. Consequently the existence of the tear tab 16 adds little or no bulk Ato a capped bottle, so that the latter may be handled andstored' inthe usual manner.

It is important or highly desirable for purposes of strength that the soldered slit 14 extend less than halfway across the top a. When this condition is observed the stress imposed on the soldered joint as a result of internal container pressure will be largely radial of the cap, hence in a direction lengthwise of the solder llct, and the joint will withstand very high internal pressures. However, if the slit were to extend more than half way across the cap, it is .apparent that the joint is required to assume a ltransverse loading and more readily tears apart as internal container pressure is increased. By observing the condition described, namely that the length of the slit be appreciably less than the radius of the cap (such as about 3%; vthe radius) the specific strength of the soldered joint between the slit edges need not be great, and as a result the joint will tear :apart readily when the tear tab 16 is grasped and pulled outwardly and upwardly in order toV openthe capped container (Figure 6).

It will be evident that the specific strength of the soldered joint between the edges of slit 14l may be varied byv any of different production control methods. For instance, the cross-sectional form and the spacing between the flanges of the slit edges will control the elfectivebonding area and the strength of a solder fillet received between the flanges. The type of solder usedV and the type efflux affect the tensile strength of the bond. Likewise the strength of the llet may be varied by removing some of the solder material therefrom with' a conventional wiper before the solder has set. Furthermore, the type and gauge of the plate material used in the cap will affect-the strength of the joint, since the stiffness ofthe platema terial is a factor.

In place of solder asthe bonding agent used informing with the edges ianged to receive a fillet of .binder substance' therebetween.

A suitable manufacturing technique for producing the improved crown cap out of tinplate and with a Vsolder fillet is illustrated in Figures Y7 and 8. An elongated strip` ofsheet material from which thelcaps areto be cut is fed through the initialfeed rolis and between elements which simultaneously cut a longitudinal kslit and flange theslit edges inza single operation. These elements coinpriseia circumferentially grooved bucking roll above the strip and a cooperating rotary knife beneath the strip. The groove in the ybucking rolllaccornmodates the twoanges formed in' thcstrip as Vthelknife bladepresses through the strip.

material. The-annular knife blade occupies only 'a lfraction of thocircumference of the blade support, so that as the elongated lstrip advances between the rolls lhanged slits of predetermined length are made in the strip atappropriate uniform interval spacings-along the lengthgof the, slit.

.A short length-ofstrip .material S havingla slit with.;

flanged edges formed by the rotaiy knife is shown in Figure 7. In the same iigure the dotted outlines O1 and O2 of the two cap blanks are also shown to indicate the relationship between the slit and the blanking die cutting edges by which two caps may be cut economically from the length of sheet material S in which a single slit is formed having edges bonded together .before the blanking and forming operations.

After passing Ithe slitting and ange-forming knife, the strip material Vmoves through, Iadditional, feed rolls and through apparatus for applying the solder fillet between the flanged edgesof the-slit. As the strip advances beyond the secondset` of feed rolls the flanged edges are wiped by a ux roll, to cover the surface areas to be soldered with a soldering flux, passed through a preheater which raises the temperature of the strip in order to receive the solder properlyJ and then passed through the soldering rolls which' apply molten solder to form the llet in the space between the slit anges.` Excess solder is wipedoi by the linen wiper roll before the strip passes through Ian, air blast'cooling unit. Finally the strip passes into the guides of a blanking `and forming press by which the individual cap'sare cut and crimped in the intended manner. Thes'peci'c details of the apparatus mentioned above lare Anotdescribed since the techniques involved are generally lwell known in the, art and since the particular techniques used may vary considerably. Suice it Vto say that the improved' hand-rupturable lcrown cap may be manufactured readilyon a mass production basis and at` low cost' Yaccording Vto well known basic manufacturing methods. A

It is' important to note that the steps of cutting the capl -blanks"`fro`m 'the strip Amaterial S and forming the crown caps out oftheblanks do not impair the soldered joint between the edges of slit 14. While the crimping operationV imposes vconsiderable stress on the cap material',the strength of the solder llet is adequate to withstand Vthese'stre'sses,l and yet it will not be so great as to resistv tearingof the joint when a capped bottle is to be opened by the 'described method using the tear tab 16. An otherwise conventional crown cap yforming die may be usedlbyp'roviding a shallow groove or slit in the die to accommodate" thelupturnedfia'nges of the slitf14. In fact, the -anges 'are usednto `advantage 4in the blanking die since they :may be used as'an indexing means -by which the positioning'of `the stripS "may be maintained as' it is advanced` intolthe space between the blanking die elements, .these :flanged edges sliding in a slit leading into the die.

Breferablyin or after the process of forming the wherg'it willaddJno. arpreciablebulk t0 the cappedv bQtteA-analwill not interim with yits regalar handling.,

and storage.

The tear tabridfrnay beudipped in Ka thermoplastic substance if.. desired f for providing smooth sur-v faces lWith I claim as my invention:

l. Ahandrupturable crowncap comprising a cap body includ a single slit thereinjcpnimencing lattklieelrlg'e of Vsaid Vskirt and. .extending.substantially.unnterrurtdlv therefrom Klip- Wardly yacross the `width of said skirtand at least part way across .the top, said capbjody beingotherwiseun- ,.Acircularjk top anda crimpedfannular skirt extendingAdependnaly ftlsfsfaene Said CP'bOdY having weakened, a binder substance joining the slit edges together in a sealed joint extending continuously the length of said slit, and a handle element projecting from said skirt at a location adjacent the end of said slit to permit tearing of said slit joint by progressive shearing action applied through said handle element commencing at the end of said slit, said slit edges being anged outwardly along the length of the slit to dene a groove therebetween receiving a lllet of the binder substance.

2. The crown cap dened in claim 1, wherein the slit extends radially inward of the crown cap and terminates short of the center thereof.

3. A hand rupturable crown cap of sheet metal comprising a cap body including a circular top and a crimped annular skirt extending dependingly therearound, said cap body having a slit therein commencing at the edge of said skirt and extending uninterruptedly therefrom upwardly across the width of said skirt and radially inward of said top, terminating short of the center thereof, the edges of said slit being anged outwardly continuously along the length of said slit, a solder fillet joining the anged edges of said slit together in a sealed joint ex tending continuously the length of said slit, and a handle element projecting from said skirt at a location adjacent the end of said slit to permit tearing of said slit joint by progressive shearing action applied to said handle element commencing at the end of said `slit.

4. The hand rupturable crown cap defined in claim 3, wherein the handle element comprises an integral extension of the skirt adapted to lie close alongside the neck of a container carrying said cap, and to be bent outwardly therefrom for use as a pull tab in tearing open the slit joint in order to remove the cap from the container.

5. The hand rupturable crown cap defined in claim 4,

wherein the pull tab has a dimple formed in the end' thereof to facilitate grasping the same as a handle, said dimple having a convexvside adapted to lie substantially in contact with the neck of the container.

6. A hand rupturable crown cap comprising a metal cap body including a substantially circular top and a crimped annular skirt extending dependingly therearound said cap body being slitted from the edge of said skirt upwardly and across said skirt and inwardly of said top at least part way across said top, the slit edges being joined together by solder to form a sealed connection between said edges having Istrength sucient to withstand the cap-forming operation, the slit edges being anged outwardly to form a re-entrancy therebetween extending the length of the slit, and the solder comprising a llet occupying said re-entraucy and presenting a surface inside the cap which is substantially flush with the inside surface of the cap.

7. A hand rupturable crown cap comprising a metal cap body including a substantially circular top and a crimped annular skirt extending dependingly therearound, said cap body being slitted from the edge of said skirt upwardly and across said skirt and inwardly of said top at least part way across said top, the slit edges being joined together by solder to form a sealed connection between said edges having strength suflicientto withstand the cap-forming operation, the slit edges being flanged outwardly to form a re-entrancy therebetween extending the length of the slit, and the solder comprising a fillet occupying said re-entrancy and presenting a surface inside the cap which is substantially flush with the inside surface of the cap.

References Cited in the le of this patent UNITED STATES PATENTS 598,952 Neuendorif Feb. 15, 1898 811,894 Alden Feb. 6, 1906 1,026,282 Schmitt May 14, 1912 2,110,097 Sebell Mar. 1, 1938 2,176,898 Fried Oct. 24, 1939 2,648,459 Peck Aug. 11, 1953 FOREIGN PATENTS 429,098 France July 6, 1911 

